Nearly 40 million Americans live more than an hour's drive away from the nearest trauma hospital, researchers reported.

Action Points

Explain that nearly 40 million Americans live more than an hour's drive away from the nearest trauma hospital, especially people in rural areas.

Note that the study did not address whether patients who lack easy access to trauma care experience unnecessary morbidity and mortality as a result.

Nearly 40 million Americans live more than an hour's drive away from the nearest trauma hospital, researchers reported.

That figure includes 12% of people living in cities and 31% of those living in rural areas, according to Renee Hsia, MD, of the University of California San Francisco, and Yu-Chu Shen, PhD, of the Naval Postgraduate School in Monterey, Calif.

And some groups -- including African Americans and the foreign-born -- are more likely to have more limited access to a trauma hospital, Hsia and Shen reported in the January issue of Archives of Surgery.

The findings come from an analysis that linked 2000 census data with the location of trauma hospitals as of 2005, the researchers explained.

The study was prompted by concerns about disparities in trauma access across the U.S., which has worsened as increasing numbers of trauma hospitals close their doors in the face of underfunding and other challenges, they noted.

But, while the study correctly underscores the need for a "thoughtful" distribution of trauma centers, it has an important gap, according to Justin Dimick, MD, of the University of Michigan in Ann Arbor, Mich.

In an invited critique, he argued that the focus on access rather than outcomes of care is a key limitation. The question, he said, is: "Do patients who lack easy access experience unnecessary morbidity and mortality as a result?"

Those who make decisions about healthcare, Dimick concluded, will be more likely to act on disparities in access if studies can show they affect patient care.

Hsia and Shen defined access in terms of the distance between a trauma facility and nearby ZIP codes -- within 10 miles, between 10 and 30 miles away, and more than 30 miles away -- and then converted those distances into driving times: less than 20 minutes, 20 to 60 minutes, and more than 60 minutes, respectively.

They defined ZIP codes as having high, medium, or low shares of vulnerable groups, depending on their relationship to the national population distribution of that group. So, for instance, a ZIP code was considered to have a high share of African Americans if the local percentage was in the upper third of the entire black population distribution in the U.S.

Hsia and Shen looked at ZIP code populations on the basis of race and ethnicity, foreign origin, economic status, and age.

They found:

In urban areas, 67% of the population lived within a 20-minute drive of a trauma center, 21% were within an hour's drive but more than 20 minutes away, and 12% were more than an hour's drive away.

In rural areas, the corresponding figures were 24%, 45%, and 31%, respectively.

Urban ZIP codes with a medium share and rural ZIP codes with a high share of African Americans were more likely to have difficult access -- defined as a drive time of more than an hour. The odds ratios were 1.25 and 1.35, respectively, and were significant at P<0.05.

Urban ZIP codes with a high and medium share of foreign-born residents were more likely to have difficult access, with odds ratios of 2.18 and 1.65, both significant at P<0.01.

Urban and rural ZIP codes with a high share of the so-called "near poor" -- those with incomes between the federal poverty line and twice that income -- had an increased likelihood of difficult access. The odds ratios were 1.52 and 1.69, and were significant at P<0.05 and P<0.01, respectively.

In noting the study's limitations, the researchers cautioned that they only looked at physical access to trauma care and that other factors -- including money, language, and cultural barriers -- may also play a role in restricting access to care.

It is also possible that the five years between the data sets may have introduced measurement errors. As well, the study did not account for possible aeromedical transport in some rural areas, they noted.

The study was supported by the Robert Wood Johnson Foundation and the NIH. The authors made no financial disclosures.

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